Much of the focus on the need to increase tree canopy and vegetation in urban areas has been on areas with higher housing density and on public land. There are also many concerns about the loss of vegetation in our local suburbs arising from the demolition and rebuilding with larger houses. Larger houses are not the only problem. More area of the front yard is being covered in concrete driveways.

A recent study led by Peter Davies, professor of sustainability at Macquarie University, has quantified the impact of the increasing footprint of rebuilt houses in a sample of middle-ring suburbs where low density housing still dominates. The paper was published in the Cities journal and it argues for more prescriptive and enforceable controls to protect urban green space.

The study looked at the changes from 370 knock-down rebuilds in the Ryde and Winston Hills areas. They found that the average front yard area reduced by 28 m² arising from the planning policies permitting a shortening of the distance between the building line and the front boundary. But the more significant aspect was the change in the composition of the front yard. The figure below shows the typical changes. The house on the left is the site before redevelopment (February 2010) and the house on the right is the same house after redevelopment (December 2023).

This table summarises the results.

Backyard area changes were not analysed but they are shrinking too.

Another way of looking at the data is that the average front yard coverage went from:

• driveway: 19.4 to 37.4%
• garden: 68.6 to 45.4%
• hard landscaping: 12 to 17.2%

The original houses in the study generally had a front yard with larger trees, gardens and lawns. Houses were L-shaped but now are square or rectangular. Driveways usually accommodated one car often with two concrete strips and grass in between. After the rebuild the houses often have more formalised and paved front yards and driveways are widened to accommodate a double garage. There is also the trend for front yards to be fenced off with tall hedges that require regular pruning and provide limited habitat. Is it better to have privacy or to create a friendly environment where one can chat with the neighbours?

Most councils’ Development Control Plans (DCPs) emphasise minimising driveway areas in favour of deep soil and garden areas but this has been disregarded in favour of more car parking accommodation. The DCPs in these council areas don’t help as they require off-street parking for two cars. Nevertheless, this expansion in driveways occurred despite local policy intent. Ryde's DCP states that:

Hard paved areas are to be minimised, and at a maximum, are to be no more than 40% of the front garden areas.

Parramatta's DCP that covers Winston Hills requires:

A minimum 30% of the total site area to be provided as deep soil, with 15% at the front yard.

The analysis showed canopy cover has declined by an average of 62% across all lot sizes diverging sharply from the objectives of local landscaping controls.

Ryde's DCP mandates the retention of: ‘significant natural features, particularly mature trees and other vegetation’ and requires: ‘at least one tree capable of reaching a mature height of 10 metres with a spreading canopy’ in the front garden.

Parramatta's DCP similarly promotes tree planting at the front and rear to ‘soften the built environment and encourage continuity of the landscape pattern’.

NSW's planning law does little to codify minimum landscape requirements within mandatory controls, known as environmental planning instruments, which include state environmental planning policies (SEPPs) and local environment plans (LEPs). Rather, these are relegated to DCPs created by local councils. DCPs provide the practical and detailed planning and design as recommended controls, as demonstrated by the controls in the Ryde and Parramatta DCPs. But DCPs have a subordinate role in planning and development assessment.

Planning rule changes that have applied to detached housing under the complying development policy since 2009 have increased floor space ratios, relaxed setback provisions, allowed greater use of paving and decks. Of course, the builders of these new houses don’t have to choose the maximum footprint but the mindset seems to be that a larger house is more desirable than a natural environment. Why? Prospects of a higher capital gain? Less garden to care for?

Landscaping and gardens come outside the statutory planning of SEPPS and LEPs. Policies and guidelines such as those produced by the Government Architect lack legal enforceability. Basically the development prerogative overrides the goals of sustainability. Lip service is being paid by politicians and government planners to the goals of biodiversity improvement and controlling the urban heat island impacts.

Consequences of loss of garden space

These losses of landscaped areas have adverse impacts on ecosystems services including reducing the urban heat island effect, rainwater retention and loss of bird habitat and have serious implications for the sustainability of Sydney. This erosion of residential green space places environmental planning goals in direct tension with private property rights.

All the above points to the situation where local council planning policies such as DCPs and LEPs are not statutory controls and cannot enforce the landscape provisions that are needed to address climate change because they are overruled by state SEPPs.

Many documents have been published by the Planning Department that advocate for landscaped front gardens to enhance streetscape character and support urban canopy targets but these are useless without mandatory development standards. There are government grant programs and tree planting exercises such as the Greening Our City program but they apply to public land.

Urban heat policy for land use planning statement

NSW Planning recently released a policy statement on urban heat and sought feedback from the community. This policy is part of drafting a Climate and Natural Hazards SEPP that will define planning controls that respond to these risks. The policy aims to ensure that urban heat is a consideration for development, and that where possible development contributes to cooling the local environment, supporting increased community and landscape resilience.

It includes well-meaning statements like:

Land use planning can play a role in promoting overall quality of life in the context of ongoing increases in temperatures, as well as supporting wellbeing during heatwaves by designing cool refuges in homes, public spaces and outdoor areas.

The objectives of the policy include encouraging the adaptation of existing development to improve heat resilience and contributing to the shaping of urban environments to support health and wellbeing during heatwaves and hot days. It advocates:

Designing urban structure to retain and integrate existing natural assets and enhance passive cooling, incorporating greening and water into new development for cooling, and minimising heat absorbent materials and surfaces.

This all sounds a good policy but the current planning system will make this impossible to implement in established suburbs. The guidelines for landscaping around all types of developments must be reviewed to allow for more vegetation and trees and authorities must be able to ensure that certifiers and councils enforce these requirements and ensure that the trees survive. Land areas for deep soil planting must be adequate for the survival of trees tall enough to provide the shade canopy objectives.

The Climate Change and Natural Hazards SEPP, as the over-riding policy, needs to include clear, quantitative urban tree canopy and deep‑soil standards on all development sites.

As the Davies paper concludes:

Urban planning reform is urgently needed to embed minimum standards for green space and canopy cover at the site level, ensuring that urban greening targets translate into tangible local outcomes.

Attending the briefing by new Invasive Species Council CEO Jack Gough and his team in March was a highly informative and ultimately uplifting experience. Former CEO Andrew Cox can be assured that the organisation he guided to become Australia's leading voice in tackling invasive species, is powering on with renewed energy, passion and vision with comprehensive strategic plans of action.

We first heard about the devastating effect that fire ants are having in SE Queensland. Fire ant nests can be extensive with more than 3 million aggressive inhabitants. Outdoor school excursions have been curtailed due to bite risk factors and if an excursion permission is granted, teachers carry epi-pens in their first-aid kit. An ambulance must be called any time a child receives a bite. The devastation to wildlife is also significant, with echidnas, koalas being killed by swarming ants. Pets are also a casualty. Ant attacks on stock animals are a major cost to agriculture. Such is life in a fire ant region.

The good news is that fire ants can be eradicated with secure, sufficient, sustained funding. Northern NSW is now clear of fire ants and eradication could be achieved in Qld if immediate suppression funding to tackle high density ant sites is provided along with sustained funding to keep the eradication program on track. This is a major campaign for the Invasive Species Council.

Another good news story is the return of Kangaroo Island dunnart numbers as a result of the near eradication of feral cats and de-sexing of domestic cats on the Dudley Peninsula. The island is in reach of being a world leading, island-wide wildlife haven.

The Invasive Species Council is also campaigning to establish a nationally coordinated approach to invasive weed management. Introduced buffel and gamba grasses are creating mono-cultures and fuelling grass fires of much higher intensity that scar country, change landscapes, harm cultural sites and erode living indigenous knowledge that connects people to place.

Other challenges the Invasive Species Council are addressing are:

• preventing the next rabbit plague
• preventing wildlife diseases
• protecting native parrots
• driving co-ordinated long-term responses to invasive environmental threats in Qld
• wild deer control
• feral horse control in Kosciusko National Park

The Invasive Species Council’s vision is:

To be the catalyst which drives a lasting shift in government, communities and culture to save wildlife, stop extensions and protect Australia’s forest and rivers.

Big dreams, but this skilled, enthusiastic, politically savvy, focussed team looks to have the campaign strategies in place to advocate and achieve what I hope are the goals we all want.

Check out their website and download a copy of their strategy, Standing up for nature: A bold strategy to keep Australia safe from invasive species.

By Deborah Gray

The first stage of the redevelopment of the Hornsby Quarry, the Crusher Plant Precinct, was opened at the end of March. This precinct takes its name from the former industrial plant that once crushed volcanic rock from the quarry for use across Sydney. The area has now been reimagined for passive recreation with lawns, picnic shelters and barbeque facilities.

There is a spectacular lookout over the quarry void displaying the rare geological feature, the volcanic diatreme wall, and the dense bushland vegetation. There is still much to do with plans for walking and cycling tracks and an amphitheatre next to the lake within the quarry. There is still major work required to regenerate the natural areas and remove heavy weed infestations.

The music was great, but WOMADelaide also features an information series called The Planet Talks, with presentations on environmental, sociological and political themes. This year's included a session called Oceans Calling and featured a talk highlighting the size, scale and demise of the Southern Australian oyster reefs. These reefs once fringed Australia’s southern coastlines on a scale that rivalled the Great Barrier Reef, but today only roughly 8% of them survive due to excessive harvesting, trawling and dredging, including for building materials and cement. Speaker Dominic McAfee of Adelaide University highlighted the mind blowing scale of the reefs and their loss, and spoke also about restoration projects.

The SA algal bloom

What has been called an algal bloom is actually of the dinoflagellate species Karenia cristata. Dinoflagellate plankton are protists, that is a broad group neither plants nor animals but somewhere in between. Some can photosynthesise like plants, while many behave like animals and are propelled by whip-like tails, hunting and consuming prey. Karenia species are responsible not only for the South Australian bloom but for toxic red tides, and the poisons they produce are known as brevetoxins. We learnt from 4 Corners coverage on ABC TV on 16 March that dinoflagellate blooms are a globally significant problem, Florida being especially prone.

The autumn edition of Wild magazine featured a full page article on the bloom:

By spring 2025, the bloom of harmful dinoflagellates had spread across more than 4,500 km² of coastline, releasing devastating toxins at an intensity local marine life could not withstand. The impact was fast and brutal, with countless animals like the iconic leafy sea dragon washing up dead on beaches across SA. Local tourism collapsed, commercial fishers hauled in empty nets, and experts couldn't predict an end to it.

Then the article went on to say:

But amid the devastation, a quieter story was unfolding – one that pointed to a powerful, nature-based solution already taking root along Australia's shores. For nearly a decade, The Nature Conservancy's Reef Builder project has been rebuilding the country's lost temperate shellfish reefs, systems once so vast they stretched along the southern coastline twice the length of the Great Barrier Reef. These reefs, formed by billions of native filter-feeding shellfish, act as the kidneys of the ocean, cleaning water and forming natural reef structures to stabilise shorelines and support marine biodiversity. In August 2025, local ecologists visited one of The Nature Conservancy's restored reefs off Glenelg, pulled up a handful of oysters, and discovered something extraordinary – the oysters were eating Karenia dinoflagellates through their filter feeding.

Conclusion

It’s a complex and confusing story. The loss of the temperate oyster reefs is catastrophic, but the ability of oysters to consume dinoflagellates has been demonstrated in the research co-ordinated by The Nature Conservancy. This may appear contradictory however oyster farmers interviewed on 4 Corners claimed their oysters had actually been poisoned by ingesting dinoflagellates. Then one has to question why, when the reefs are long devastated, has this major bloom event only just happened? What other factors were in play in 2025 to tip things over the edge? Ocean warming coupled with a cold upwelling has been put forward. Floodwater from the Murray has also been cited but subsequently dismissed. There clearly has been progress, but the 4 Corners coverage shone a disturbing torchlight into the inadequately informed, devious, tardy and unsupportive responses of South Australia’s government and public service, including critical comments from a Florida expert.

By John Martyn